* \do(single|double|etc)empty behaviour
@ 2010-12-15 18:40 Marco Pessotto
2010-12-15 22:56 ` Wolfgang Schuster
0 siblings, 1 reply; 3+ messages in thread
From: Marco Pessotto @ 2010-12-15 18:40 UTC (permalink / raw)
To: ntg-context
Hello there.
I was writing a small macro to emulate a custom \part command, and I
broke my head against \dosingleempty (but finally I won).
Why this example is working:
%%%%%%%%% start %%%%%%%%%%%%%%%%%
\definelist[talpart]
\define\talpart{\page[right]%
\blank[2*big]%
\startalignment[center]%
\dosingleempty\doTalPart}
\def\doTalPart[#1]#2{%
\iffirstargument
debug: I have the optional arg
\bfc#1\blank[2*big]
\writetolist[talpart]{}{{#1. }#2}
\else
debug: I don't have any arg
\blank[2*big]
\writetolist[talpart]{}{#2}
\fi
\bfd#2
\stopalignment
\blank[2*big]
}
\starttext
\placelist[talpart]
\talpart[optional]{With optional argument}
\input knuth
\talpart{No argument}
\input ward
\stoptext
%%%%%%%%%%% stop %%%%%%%%%%%%%%%%
While this, the original one, is definitively not working?
%%%%%%%%% start %%%%%%%%%%%%%%%%%
\definelist[talpart]
\define\talpart{\dosingleempty\doTalPart}
\def\doTalPart[#1]#2{%
\page[right]
\startalignment[center]
\blank[force,2*big]
\iffirstargument
debug: I have the optional arg
\noindent{\bfc#1}\blank[2*big]
\writetolist[talpart]{}{{#1. }#2}
\else
debug: I don't have any arg
\blank[2*big]
\writetolist[talpart]{}{#2}
\fi
{\noindent \bfd#2}
\stopalignment
\page[left]
}
\starttext
\placelist[talpart]
\talpart[optional]{With optional argument}
\input knuth
\talpart{No argument}
\input ward
\stoptext
%%%%%%%%%%% stop %%%%%%%%%%%%%%%%
It's unclear to me how the arguments are passed between macros.
Probably it's just a matter of knowledge of TeX macro programming (which
obviously I don't have).
My source of inspiration was:
http://wiki.contextgarden.net/Commands_with_optional_arguments
Bests
--
Marco
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If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: \do(single|double|etc)empty behaviour
2010-12-15 18:40 \do(single|double|etc)empty behaviour Marco Pessotto
@ 2010-12-15 22:56 ` Wolfgang Schuster
2010-12-15 23:31 ` Marco Pessotto
0 siblings, 1 reply; 3+ messages in thread
From: Wolfgang Schuster @ 2010-12-15 22:56 UTC (permalink / raw)
To: mailing list for ConTeXt users
Am 15.12.2010 um 19:40 schrieb Marco Pessotto:
>
> Hello there.
>
> I was writing a small macro to emulate a custom \part command, and I
> broke my head against \dosingleempty (but finally I won).
>
> […]
>
> It's unclear to me how the arguments are passed between macros.
> Probably it's just a matter of knowledge of TeX macro programming (which
> obviously I don't have).
Your test with \iffirstargument fails because you perform it after \startalignment
which has itself a argument which sets \iffirstargument to true, a better way to
check for content of the optional argument is \doifsomethingelse.
\def\talpart
{\dosingleempty\dotalpart}
\def\dotalpart[#1]#2%
{\page[right]
\blank[force,2*big]
\startalignment[center]
\doifsomethingelse{#1}
{{\bfc#1}\writetolist[talpart]{}{#1. #2}}
{\writetolist[talpart]{}{#2}}%
\blank[2*big]
{\bfd#2}
\stopalignment
\page[left]}
Wolfgang
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://tex.aanhet.net
archive : http://foundry.supelec.fr/projects/contextrev/
wiki : http://contextgarden.net
___________________________________________________________________________________
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: \do(single|double|etc)empty behaviour
2010-12-15 22:56 ` Wolfgang Schuster
@ 2010-12-15 23:31 ` Marco Pessotto
0 siblings, 0 replies; 3+ messages in thread
From: Marco Pessotto @ 2010-12-15 23:31 UTC (permalink / raw)
To: ntg-context
Wolfgang Schuster <schuster.wolfgang@googlemail.com> writes:
> Am 15.12.2010 um 19:40 schrieb Marco Pessotto:
>
>>
>> Hello there.
>>
>> I was writing a small macro to emulate a custom \part command, and I
>> broke my head against \dosingleempty (but finally I won).
>>
>> […]
>>
>> It's unclear to me how the arguments are passed between macros.
>> Probably it's just a matter of knowledge of TeX macro programming
>> (which obviously I don't have).
>
> Your test with \iffirstargument fails because you perform it after
> \startalignment which has itself a argument which sets
> \iffirstargument to true, a better way to check for content of the
> optional argument is \doifsomethingelse.
>
> \def\talpart
> {\dosingleempty\dotalpart}
>
> \def\dotalpart[#1]#2%
> {\page[right]
> \blank[force,2*big]
> \startalignment[center]
> \doifsomethingelse{#1}
> {{\bfc#1}\writetolist[talpart]{}{#1. #2}}
> {\writetolist[talpart]{}{#2}}%
> \blank[2*big]
> {\bfd#2}
> \stopalignment
> \page[left]}
>
> Wolfgang
>
Thanks a lot for your explanation. I've added a "pitfalls" section to
http://wiki.contextgarden.net/Commands_with_optional_arguments#Pitfalls
(well, it was a pitfall at least for me)
--
Marco
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://tex.aanhet.net
archive : http://foundry.supelec.fr/projects/contextrev/
wiki : http://contextgarden.net
___________________________________________________________________________________
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